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Deep-sea nodule and crust ecosystems: benthic assemblages of manganese nodules and cobalt-rich crusts SPC-EU EDF10 Deep Sea Minerals Project Workshop, Nadi, Fiji. June 2011 Malcolm Clark National Institute of Water & Atmospheric Research, New Zealand

Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

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Page 1: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Deep-sea nodule and crust

ecosystems: benthic

assemblages of manganese

nodules and cobalt-rich crusts

SPC-EU EDF10 Deep Sea Minerals Project Workshop, Nadi, Fiji. June 2011

Malcolm Clark

National Institute of Water & Atmospheric

Research, New Zealand

Page 2: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Outline

• Background: geological context

• Deep-sea benthic biodiversity

– Manganese nodules

– Cobalt-rich crusts

• Seamounts

• ISA and CenSeam Workshops

• Environmental considerations

• Conservation issues

Page 3: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

• Focus on cobalt-rich

ferromanganese crust

– partly because

nodules have

received a lot of

attention from the

ISA (several very

good reports)

– partly because crust

are common in the

SW Pacific region

– partly because of

new work that hasn’t

yet been widely

disseminated

Country MN CRC SMS

Kiribati √ √

Cook Islands √

Tuvalu √ √

Samoa √

Tonga √

PNG √

Solomon Islands √

Vanuatu √

Fiji √

Marshall Islands √

Federated States of

Micronesia

Niue √ √

Page 4: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Manganese nodule fauna

• 4000-5000 m depth-abyssal plain

• Seafloor primarily soft-sediment

• Hard substrate seamounts & nodules

• Attached fauna – mainly protozoans (CCZ, 73 spp)

– 90% Foraminifera

– few metazoa taxa (CCZ, 17 spp)

– limited macrofauna (polychaetes, bryozoans, sponges, holothurians)

Page 5: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Manganese nodule fauna (2)

• General regional fauna – highly diverse soft sediment communities

– Nematodes, polychaetes, amphipods, isopods

– Less diverse and abundant surface macrofauna

– sponges, octocorals, holothurians

Page 6: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Bluhm 1994

Page 7: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Low abundance

Comparison of epibenthic macrofauna in the SW Pacific

SOPAC-Japan surveys 1990s (Fukushima 2007)

Page 8: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Polychaete biodiversity

Many families (>30): a worm is not just a worm

Possibly high levels of

endemism (in terms of 100-1000

km spatial scale)

Smith et al. 2006

Smith-ISA 2008

Page 9: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Understanding drivers key to

successful conservation

• Manganese nodules

– specialised attached fauna (substrate)

– depth-based faunal pool

– food availability (flux gradients)

– nodule size and shape

– location (substrate mix)

Decades of research in

the CCZ, East Pacific

Page 10: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Effects of Productivity

Even at great depth, gradients in

the amount of “food” sinking to

the seafloor has a major effect

Mincks & Smith 2006

Page 11: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Ferromanganese Crust fauna

• 800-2500 m depth-

seamounts/guyots

• Seafloor hard substrate (no

sediment)

• Extensive areas (continuous, not

small scale like nodules)

• Ability for high densities of sessile

fauna characteristic of many

deep-sea seamounts

• Seamounts are a very prominent

topographic feature in the Pacific

Ocean

Page 12: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Global estimates of seamounts

Seamounts

(>1000m high)

33,400

Knolls

(250-1000m)

138,400

Yesson et al.

2011

Page 13: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Central Pacific region

Large number of seamounts (excluding knolls) (14,300)

Large number of seamounts at Co-crust depths (4,100)

Cobalt-Rich Zone defined by orange polygon

Page 14: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Biological data sources

• Few published studies specifically on

ferromanganese crust fauna

– indicated low diversity, low abundance

– Mostly from North Pacific seamounts, Cross

Seamount in particular

• Global seamount database

– SeamountsOnline

– OBIS

– About 20,000 records

– However, very few from CRZ

Page 15: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

2006 ISA Workshop

• ISA Workshop in association with CenSeam (DAWG) on Deep sea cobalt-rich ferromanganese crust deposits and distribution patterns of seamount fauna.

• Assessed data sets in Atlantic and Pacific

• Some preliminary analyses done (mainly SW Pacific, Nazca & Sala y Gomez chain)

• Not much data were available from the core areas of interest (few seamounts sampled well)

• But it was clear that more could potentially be done using data sets from Hawaii

• CenSeam proposal 2007 funded by ISA

• Subsequent analyses and report 2009

Page 16: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

HURL Video Log Database

• Records of all fauna seen in submersible dives

• Pisces IV and V

• Subset of 13,175 records

• 200 -2000 m

• 16 sites, 83 dives

• Benthic invertebrates only

• 448 species

Page 17: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Cobalt-rich seamounts on Hawaiian seamount chain based on

CRZ defined by Jim Hein

Page 18: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Further NW along Hawaiian seamount chain less cobalt-rich

Page 19: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Hard substrate fauna

• Corals and sponges dominant

Page 20: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

MDS of Cobalt zone

R =0.042, p=0.315

Green=Co-rich

Blue=non Co-rich

Page 21: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

By Location

Abbrev LocBBB

Raita

E Nhampton

W Nhampton

W St R

Nihoa

East FFS

Maro

W Lis

NW Kure

Nero

Cross

WestPac

Pioneer

E Lay

E Neck

2D Stress: 0.23

Page 22: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Mean Depth of Dive

Page 23: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

2009 Conclusions

• Distribution of benthic communities is not related

to cobalt-rich crust

• Strong correlation to depth

• Location also important

Clark, M., C. Kelley, A. Baco, A. Rowden.

(2011) Fauna of Cobalt-rich

ferromanganese crust seamounts. ISA

Technical Study No. 8

Page 24: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

2011 Workshop

• More image data available from HURL

• Substrate information included

• Faunal density-abundance measures

• Analyses ongoing

• Preliminary results:

– Some similar

– Some differ

Page 25: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Preliminary results

• Depth is a key driver of community composition

• Substrate is important driver of community

composition

• Mn-crust does influence community composition

zero/low (<0.20)

low / medium (0.21-0.80)

high (>0.80)

Mn-Crust

Page 26: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Preliminary results (2)

• The effect of the Hein CRZ was also significant.

(PERMANOVA, CRZ nested within depth)

zero/low (<0.20)

low / medium (0.21-0.80)

high (>0.80)

Mn-Crust

Co-rich Zone

Page 27: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Implications for Co-crust Management

• Co-rich crust seamounts may have different

fauna from non cobalt-rich crust

• Implies control-exploitation sites need to be

chosen carefully

• Depth is a critical consideration in any design

of conservation areas

• Results are preliminary, hope ISA will support

further work

• Knowledge of biodiversity in CRZ poor, and

much basic data needed with exploration

Page 28: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Environmental considerations

• Faunas of manganese nodule and cobalt-rich ferromanganese crusts are very different

• Hence need to consider impacts separately, especially given the shallower crust operation

• Mining of either resource is not “sustainable” in terms of localised impact

• So the management objective is not to “preserve” but to balance exploitation and conservation

• Spatial management is the likely solution, based on good science to inform about impacts and assessment of risk.

Page 29: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Existing guidance

• Many countries have developing environmental policies and guidelines

• But need more than just “do an EIA”

• Standards and guidelines

• ISA reports

– environmental guidelines for polymetallic nodules

– guidelines for polymetallic sulphides and cobalt-rich crusts

• International Marine Minerals Society code

• InterRidge “code of conduct” for scientific operations also

Page 30: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Key impacts to consider

• Potential benthic impacts – direct physical impact of mining/sampling gear

– smothering/burying of animals by sediment

– clogging of suspension feeders

– toxic effects with metal release

– loss of essential habitat (spawning/nursery grounds etc)

• Potential water column impacts – plankton/mesopelagic fish mortality

– bioaccumulation of toxic metals though food chain

– sediment plume through water column

– potential oxygen depletion

– effects on deep-diving marine mammals

• Potential surface impacts – reduction in primary production through sediment plume shading

– effects on behaviour of surface/deep-diving mammals and birds through changes in water clarity

Page 31: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Key biological research elements (1)

• Physical topography – Co-crust associated with large seamounts – Variable habitat on different scales – mining sites likely to be extensive – substrate type (sediment disturbance)

• Oceanography – current flows, stratified through water

column – seamount effects important – important for spatial scale of animal

distribution and dispersal, as well as any mining impacts

– strong linkage with chemical composition/toxic release, and turbidity

Page 32: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Key biological research elements (2)

• Benthic biodiversity – mega-epifauna down to meiofauna, infauna – determine species distribution &

abundance – stratification by topography/habitat can be

small scale, but regional biodiversity setting can be large scale

– of special note are sessile animals, low dispersal capability, slow growth rates, restricted distribution. i.e. high vulnerability to impact

• Pelagic biodiversity – less developed science than benthic – maybe of less immediate concern

Page 33: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Spatial management issues

• Forget about community “recovery” or

resilience

• Need to protect areas from any disturbance

• Areas may need to be large (40% of habitat

area is possibly required)

• Entire seamount management may be

necessary (rather than sectors)

• Physical disturbance is “easy” to understand,

but indirect effects more difficult to measure

• Connectivity of habitat critical

Page 34: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Recovery is slow...very slow

Dredge track after 26 years...(CCZ)

Experimental response-

the DISCOL project

(Peru Basin)

Bluhm 2001

Page 35: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Connectivity-larval dispersal

Need to allow for dispersal WITHIN a large MPA, or

BETWEEN several smaller units

Page 36: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Sediment plume

Scale of up to 100 km for plume dispersal/settlement

Omni-directional-no clear “downstream” direction

Need for buffer to protect from mining on boundary

Page 37: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

CCZ network of “protected areas”

Page 38: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Final slide

• Scientific knowledge is limited in deep-sea ferromanganese nodule and crust environments, but sufficient to inform the first steps in developing exploration activities, and avoid undue risk to ecosystems based on inadequate information

• Successful management of deep-sea mining is reliant on a cooperative and integrated approach between all “stakeholders”

– multidisciplinary science is needed, and involve collaboration between mining and govt agencies

– the wide ranging attendance here with mining companies, policy makers, lawyers, managers, economists, scientists, conservation agencies, NGOs, societal representatives...is a great start

Page 39: Deep-sea nodule and crust ecosystems: benthic assemblages ...dsm.gsd.spc.int/public/files/meetings/MClark_Nodules_Crust.pdf · Samoa √ Tonga √ PNG √ Solomon Islands √ Vanuatu

Acknowledgments

• HURL for provision of image data

• CenSeam for coordinating analyses

• ISA for funding workshops and

publications

• SOPAC for funding participation